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From:   Florian Weimer <fweimer@redhat.com>
To:     David Howells <dhowells@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org, Ian Kent <raven@themaw.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <christian@brauner.io>,
        linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] uapi: Remove the inclusion of linux/mount.h from
 uapi/linux/fs.h
References: <163410.1659964655@warthog.procyon.org.uk>
Date:   Wed, 10 Aug 2022 11:26:30 +0200
In-Reply-To: <163410.1659964655@warthog.procyon.org.uk> (David Howells's
        message of "Mon, 08 Aug 2022 14:17:35 +0100")
Message-ID: <87zggce9fd.fsf@oldenburg.str.redhat.com>
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* David Howells:

> We're seeing issues in autofs and xfstests whereby linux/mount.h (the UAPI
> version) as included indirectly by linux/fs.h is conflicting with
> sys/mount.h (there's a struct and an enum).
>
> Would it be possible to just remove the #include from linux/fs.h (as patch
> below) and rely on those hopefully few things that need mount flags that don't
> use the glibc header for them working around it by configuration?

Wasn't <linux/mount.h> split from <linux/fs.h> relatively recently, and
userspace is probably using <linux/fs.h> to get the mount flag
definitions?

In retrospect, it would have been better to add the new fsmount stuff to
a separate header file, so that we could include that easily from
<sys/mount.h> on the glibc side.  Adhemerval posted a glibc patch to
fake that (for recent compilers):

  [PATCH] linux: Fix sys/mount.h usage with kernel headers
  <https://sourceware.org/pipermail/libc-alpha/2022-August/141316.html>

I think it should work reliably, so that's probably the direction we are
going to move in.

We'll backport this to 2.36, and distributions will pick it up.

Thanks,
Florian